A conventional over voltage protection device is installed on a printed circuit board to protect internal IC devices according to demands by each IC device. However, such design requires installing independent over voltage protection devices to prevent respective IC devices from damage by surge pulses.
Please refer to FIG. 1a, which is a top view of an IC device disposed on a conventional substrate. In FIG. 1a, there are a plurality of electrodes (11) and a grounding line (13) disposed on a substrate (12). Then, an IC device (10) is soldered to the plurality of electrodes and the grounding line. FIG. 1b is a sectional view of an IC device disposed on a conventional substrate. In FIG. 1b, we can understand the relationship among the constituent elements. Because such structure cannot provide a over voltage protection function, the IC device cannot accept the energy of surge pulses, resulting in an irrecoverable damage to the IC device.
In order to protect the IC device, several over voltage protection devices are subsequently proposed. However, those over voltage protection devices need to install individual protection devices on a printed circuit board according to the actual necessity after the IC device was manufactured and installed on the printed circuit board. Therefore, such design has the disadvantages of high design costs, wasting limited space, and providing incomplete protection to the IC device.
Therefore, there is a need to provide an IC package substrate with over voltage protection function. In this way, a plurality of over voltage protection devices are provided simultaneously to solve the problems in the prior arts that unable to provide the over voltage protection or the inconvenience in the prior arts that need to install individual protection devices on a printed circuit board. The present invention provides an IC package substrate with over voltage protection function to eliminate the inconvenience.